/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.config;

import java.util.LinkedHashMap;
import java.util.Map;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.TypeConverter;
import org.springframework.core.ResolvableType;
import org.springframework.lang.Nullable;

/**
 * Simple factory for shared Map instances. Allows for central setup
 * of Maps via the "map" element in XML bean definitions.
 *
 * @author Juergen Hoeller
 * @see SetFactoryBean
 * @see ListFactoryBean
 * @since 09.12.2003
 */
public class MapFactoryBean extends AbstractFactoryBean<Map<Object, Object>> {

    @Nullable
    private Map<?, ?> sourceMap;

    @SuppressWarnings("rawtypes")
    @Nullable
    private Class<? extends Map> targetMapClass;


    /**
     * Set the source Map, typically populated via XML "map" elements.
     */
    public void setSourceMap(Map<?, ?> sourceMap) {
        this.sourceMap = sourceMap;
    }

    /**
     * Set the class to use for the target Map. Can be populated with a fully
     * qualified class name when defined in a Spring application context.
     * <p>Default is a linked HashMap, keeping the registration order.
     *
     * @see java.util.LinkedHashMap
     */
    @SuppressWarnings("rawtypes")
    public void setTargetMapClass(@Nullable Class<? extends Map> targetMapClass) {
        if (targetMapClass == null) {
            throw new IllegalArgumentException("'targetMapClass' must not be null");
        }
        if (!Map.class.isAssignableFrom(targetMapClass)) {
            throw new IllegalArgumentException("'targetMapClass' must implement [java.util.Map]");
        }
        this.targetMapClass = targetMapClass;
    }


    @Override
    @SuppressWarnings("rawtypes")
    public Class<Map> getObjectType() {
        return Map.class;
    }

    @Override
    @SuppressWarnings("unchecked")
    protected Map<Object, Object> createInstance() {
        if (this.sourceMap == null) {
            throw new IllegalArgumentException("'sourceMap' is required");
        }
        Map<Object, Object> result = null;
        if (this.targetMapClass != null) {
            result = BeanUtils.instantiateClass(this.targetMapClass);
        } else {
            result = new LinkedHashMap<>(this.sourceMap.size());
        }
        Class<?> keyType = null;
        Class<?> valueType = null;
        if (this.targetMapClass != null) {
            ResolvableType mapType = ResolvableType.forClass(this.targetMapClass).asMap();
            keyType = mapType.resolveGeneric(0);
            valueType = mapType.resolveGeneric(1);
        }
        if (keyType != null || valueType != null) {
            TypeConverter converter = getBeanTypeConverter();
            for (Map.Entry<?, ?> entry : this.sourceMap.entrySet()) {
                Object convertedKey = converter.convertIfNecessary(entry.getKey(), keyType);
                Object convertedValue = converter.convertIfNecessary(entry.getValue(), valueType);
                result.put(convertedKey, convertedValue);
            }
        } else {
            result.putAll(this.sourceMap);
        }
        return result;
    }

}
